In-situ formed intergranular TiB2 into lightweight SiC(rGO) composite PDCs enable elevated temperature resistance for aerospace components

Abstract

Strengthening interface bonding for superior mechanical/ablation performances of SiC-based aerospace vehicle components remains a major challenge. Attractively, polycarbosilane-vinyltriethoxysilane-graphene oxide with addition of TiN/B (PVG(TiN, B)) were successfully synthesized for the first time. An ingenious route via re-pyrolyzing ball-milling-induced SiC(rGO, TiB2)p fillers/PVG(TiN, B) precursors blends was introduced to prepare lightweight SiC(rGO, TiB2) composite polymer-derived ceramics (PDCs). Interestingly, both SiC(rGO, TiB2)p and PVG(TiN, B) pyrolysis products, composed of β-SiC/SiOxCy/Cfree(rGO, TiB2), are tightly coupled by each other owing to plentiful Si-dangling bonds. In-situ formed intergranular TiB2/B4C, well compatible with amorphous ceramic network, can prevent β-SiC grain growth, strengthen interface bonding, and even hinder further crack propagation along the grain boundaries. Particularly, samples re-pyrolyzed at 1300 °C possess unique combination of good hardness (5.44 GPa), excellent fracture toughness (4.70 MPa·m1/2), high flexural strength (41.90 MPa) and outstanding compressive strength (126.33 MPa). Improved high-temperature and ablation resistance gives them distinct advantages of interlocked microstructure under exposure of butane flame. As demonstrated, SiC(rGO, TiB2) composite PDCs were developed into porous ceramics with good thermal insulation, focusing on manufacturing large-size bulk PDCs for thermal protection system of hypersonic vehicles.